Effects of elevated nitrogen and exotic plant invasion on soil seed bank composition in Joshua Tree National Park

Schneider, Heather E.; Allen, Edith B.

doi:10.1007/s11258-012-0085-6

Cited by 34 publications

(28 citation statements)

References 43 publications

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“…Cover and flowering of the other species was not affected significantly by 35N or 140N treatment (GLM; P40.1 in all the cases). Although exotic species in the seed bank can increase after N deposition 11 , we did not record any weeds or invasive species in the soil, which is consistent with the aboveground vegetation responses 5 .…”

Section: Resultssupporting

confidence: 85%

“…Despite widespread evidence of impacts of N pollution on floristic diversity and plant community structure 4,5 , studies on soil seed banks are scarce [10][11][12][13] and most are limited to short-term effects. For example, a 3-year study of N addition in a desert community found no change in the density or species richness of the seed bank 11 , while another 1-year study found that N addition increased seedling emergence 12 . One long-term study of N addition showed changes in seed bank composition in a tundra plant community 13 .…”

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Long-term nitrogen deposition depletes grassland seed banks

et al. 2015

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Nitrogen (N) pollution is a global threat to the biodiversity of many plant communities, but its impacts on grassland soil seed banks are unknown. Here we show that size and richness of an acid grassland seed bank is strongly reduced after 13 years of simulated N deposition. Soils receiving 140 kg N ha À 1 per year show a decline in total seed abundance, seed species richness, and the abundance of forbs, sedges and grasses. These results reveal larger effects of N pollution on seed banks than on aboveground vegetation as cover and flowering is not significantly altered for most species. Further, the seed bank shows no recovery 4 years after the cessation of N deposition. These results provide insights into the severe negative effects of N pollution on plant communities that threaten the stability of populations, community persistence and the potential for ecosystems to recover following anthropogenic disturbance or climate change.

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Section: Resultssupporting

confidence: 85%

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confidence: 99%

Long-term nitrogen deposition depletes grassland seed banks

et al. 2015

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“…A mix of these exotic species was planted at a total rate of 1600 live seed/m 2 . This seeding density is at the low end for naturalized annual grassland reseeding rates in the field (Dyer and Rice 1997, Hamilton et al 1999, Eviner and Firestone 2007, Schneider and Allen 2012, but was more than sufficient to create stands that achieved 100% aerial cover in the first year. All exotic grass seed was donated by Pacific Coast Seed (Livermore, California, USA).…”

Section: Experimental Design and Monitoringmentioning

confidence: 99%

Short‐term priority over exotic annuals increases the initial density and longer‐term cover of native perennial grasses

Vaughn

Young

2015

Ecological Applications

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Temporal priority can affect individual performance and reproduction, as well as community assembly, but whether these effects persist over time remains unclear, and their demographic mechanisms have been little explored. The continued dominance of exotic annual grasses in California has been commonly attributed to their demonstrated early germination and rapid early growth relative to native perennial grasses. This advantage may play a crucial role in the structure of California exotic annual grasslands, as well as in the practice of native grassland restoration. We tested whether a two-week planting advantage under field conditions increased individual survival, growth, and reproduction for four native perennial grass species and whether these effects persisted over three years. We show that short-term priority significantly increased the establishment success of' native perennial grasses. Increased density of native grass seedlings presaged later large increases in cover that were not evident in the first year after planting. Although priority effects at the individual level may diminish over time, short differences in emergence timing can have long-lasting effects on community structure. Earlier germination and faster initial growth of exotic annual species may help explain their unprecedented invasion and continued dominance of California grasslands. Finally, these results highlight the importance of priority effects for effective exotic annual control during native grassland restoration in California: initial control can increase the establishment of native perennial seedlings, which then results in long-term control by mature native individuals.

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“…Determining critical N deposition loads on specific habitats must combine manipulation experiments mimicking the frequency and temporal nature of the dry and wet N deposition at levels low enough to include the range of known N deposition, with observations on biodiversity, ecosystem processes and indicator species along anthropogenic N deposition gradients (e.g., Bobbink et al, 2010). Many manipulation experiments have been conducted to study potential impacts of N addition on ecosystems such as temperate grasslands (e.g., Morecroft et al, 1994;Horswill et al, 2008), Mediterranean shrublands (e.g., Vourlitis et al, 2009;Dias et al, 2011), deserts (e.g., Allen et al, 2009;Schneider and Allen, 2012), and the boreal tundra (e.g., Nemergut et al, 2008;DeLuca et al, 2007). However, the approach has some drawbacks, such as the limited number of years that it is practical to maintain such experiments (Duprè et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems

Ochoa‐Hueso

Maestre

Ríos

et al. 2013

Environmental Pollution

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Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3-7.3 kg N ha⁻¹ yr⁻¹) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Net ammonification and nitrification (which dominated N-mineralization) were reduced and increased, respectively, by N fertilization, suggesting alterations in the N cycle. Soil organic C content, C:N ratios and the activity of β-glucosidase decreased along the extant gradient in most locations. Our results suggest that semiarid soils in low-productivity sites are unable to store additional N inputs, and that are also unable to mitigate increasing C emissions when experiencing increased N deposition.

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Effects of elevated nitrogen and exotic plant invasion on soil seed bank composition in Joshua Tree National Park

Cited by 34 publications

References 43 publications

Long-term nitrogen deposition depletes grassland seed banks

Long-term nitrogen deposition depletes grassland seed banks

Short‐term priority over exotic annuals increases the initial density and longer‐term cover of native perennial grasses

Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems

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